微波源中同轴提取区支撑杆的理论分析与设计

Theoretical Analysis and Design of the Support Posts in Coaxial Extractor of Microwave Source

同轴提取区支撑杆的设计是MILO等同轴提取型高功率微波源设计的重要环节。本文根据场匹配原理导出了具有支撑杆的同轴提取区系统的传输方程和散射矩阵 ,并对同轴提取区各部分的微波模式进行了理论分析。对给定参数下的同轴提取区系统的散射矩阵参数进行数值计算 ,进而得到各微波模式系数 ,并对支撑杆进行了设计和参数优化。理论分析和数值计算都得出同样结论 :对一定频率的微波来说 ,若同轴波导中第一个截止模式是Hn1,则应选择n根支撑杆。这种支撑杆对TEM波的传播几乎无影响 。

The design of the support post in coaxial extractor is very important to the coaxial extracting kind of HPM sources such as MILO. According to the field matching theorem, the transmission equation and scatter matrix expressions of the coaxial extractor system with support post are educed in this paper. The characteristics of microwave modes in each part of the coaxial extractor system are theoretically analyzed. The scattering matrix parameters of this system are numerically calculated, the mode amplitudes are gained, the support leg is designed and optimized. From the theoretical analysis and numerical calculation, the same result is educed, that is if the first cut off mode of microwave at certain frequency in coaxial waveguide is H n 1 , then n posts should be chosen. This kind of support post almost has no influence to the TEM wave transmission, and it can make the beam microwave reciprocity part, mode transformation part and radiator of microwave source avoid the influence of non rotating symmetry modes.